Re: Why lang/gcc14-devel builds are failing on the build servers: needs USES= compiler:c++14-lang (or higher) instead of compiler:c++11-lang

On Feb 7, 2024, at 23:40, Nuno Teixeira <eduardo@freebsd.org> wrote:

> USES compiler is somehow deprecated as clang and gcc on base and ports supports capable compiler described in handbook:
> https://docs.freebsd.org/en/books/porters-handbook/book/#uses-compiler

Use of the likes of

USES=           compiler:c++11-lang . . .

also causes the compile commands to start with:

c++ -std=c++11  . . .

( as shows up in the log file for building lang/gcc14-devel ).

It is not just about which compiler execuable that is selected
by the  notation, it is also about telling that executable
which langauge version it is to apply. libc++ in turn does
different things for its definitions based on which standard
is used by the compiler.

Using the likes of, say:

USES=           compiler:c++14-lang . . .

would also cause the compile commands to have:

c++ -std=c++14  . . .

that would be provide the constexpr definitions
needed. Later C++ standards also would provide
those.

It is true that the default for -std=c++?? may be
-std=c++14 or later. But some things fail for use
of too recent of a standard because of changes in
the standards as they progress --so the defaults
need not work. (I've no clue of the specifics for
building lang/gcc14-devel .)

I expect that slavadore will pick a notation that
is sufficient for the builds to work.

> Mark Millard <marklmi@yahoo.com> escreveu (quinta, 8/02/2024 à(s) 05:52):
> The error on the FreeBSD build servers:
> 
> QUOTE
> /wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/config/aarch64/aarch64.cc:13095:50: error: constexpr variable 'tiles' must be initialized by a constant expression
> 13095 | static constexpr std::pair<unsigned int, char> tiles[] = {
> | ^ ~
> 13096 | { 0xff, 'b' },
> | ~~~~~~~~~~~~~~
> 13097 | { 0x55, 'h' },
> | ~~~~~~~~~~~~~~
> 13098 | { 0x11, 's' },
> | ~~~~~~~~~~~~~~
> 13099 | { 0x01, 'd' }
> | ~~~~~~~~~~~~~
> 13100 | };
> | ~
> /wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/config/aarch64/aarch64.cc:13096:5: note: non-constexpr constructor 'pair<int, char, nullptr>' cannot be used in a constant expression
> 13096 | { 0xff, 'b' },
> | ^
> /usr/include/c++/v1/__utility/pair.h:225:5: note: declared here
> 225 | pair(_U1&& __u1, _U2&& __u2)
> END QUOTE
> 
> is because C++11 did not have pair constructors being constexpr.
> C++14 (and later) does. Yet lang/gcc14-devel 's Makefile says:
> 
> USES=           compiler:c++11-lang cpe gmake iconv libtool makeinfo perl5 tar:xz
> 


===
Mark Millard
marklmi at yahoo.com